Conventionally, there is known a transfer robot that is arranged in a space formed in a equipment front end module (EFEM) and transfers a substrate, such as a semiconductor wafer.
The transfer robot typically includes an arm body and transfers a substrate, for example, by moving the arm body in a horizontal direction while holding the substrate by the arm body and an end effector provided at the tip portion of the arm body. The arm body itself is often supported by a lifting unit that can perform a raising and lowering operation.
Because products, such as a semiconductor wafer, are handled in the EFEM, it is highly required to keep the air inside the EFEM extremely clean. Therefore, downflow of clean air is often created from the upper portion of the EFEM, however, various transfer robots are also proposed that prevent contamination by particles by using an additional method.
For example, a transfer robot is proposed that prevents adhesion of particles dispersed by a disturbance of downflow by covering a transfer unit including the arm body and the lifting unit described above with a cover member (for example, see Japanese Patent Laid-open Publication H10-261690).
However, the conventional transfer robot has room for further improvement in suppression of particles generated by the raising and lowering operation. Specifically, when a transfer robot has a structure in which the above-described lifting unit is raised and lowered by protruding from a body unit (hereinafter, described as “base unit”) of the transfer robot, a substrate may be contaminated by particles dispersed from the inside of the base unit by the raising and lowering operation.